What Material Are Plastic Bags Generally Made Of?

1. Source of raw materials
The main raw materials of plastic bags are polyethylene and polypropylene, which are petrochemical products that form polymer particles after polymerization. These particles can be produced and processed into raw materials for plastic bags through chemical plants or petrochemical companies.

2. Production process
The process of producing plastic bags usually includes the following steps:

•  Material pretreatment: melt and mix the raw material particles, adjust the additive components added to the particles and control the corresponding parameters.
•  Blown film: A film blowing machine is used to extrude the molten plastic from the die to form a film.
•  Printing: Print the pattern or text to be printed on the surface of the film.
• Cutting: Cut the printed film into specified sizes through a bag cutting machine.
•  Finished product processing: The cut plastic bags are subjected to deburring, shaping and other processing procedures to make the final product.

3.Some properties and uses of plastic bag components.

• Polyethylene plastic bags (PE plastic bags): Polyethylene is polymerized and is a non-toxic material with no odor and strong chemical stability. The daily use temperature is -100~70℃, and it is often used to package food or directly package food in daily life. However, since the withstand temperature of PE plastic bags is below 70°C, they cannot contain high-temperature items.
• Polypropylene (PP plastic bag): Polypropylene is usually mixed with a small amount of ethylene in a copolymer. The raw material is a translucent colorless solid, non-toxic and odorless. Its melting point is as high as 167°C, so plastic products made of polypropylene can Heat-resistant, corrosion-resistant, and can be steam sterilized.
• Polystyrene (PS plastic bag): Polymerized by styrene, it is a colorless and transparent thermoplastic that can withstand a glass transition temperature of 100°C. It is often used to make disposable containers, such as disposable foam lunch boxes. .
• Polyvinyl chloride (PVC plastic bag): Thermoplastic resin polymerized from vinyl chloride. Vinyl chloride homopolymer and vinyl chloride copolymer are both called polyethylene resin. PVC plastic will release toxic gases such as hydrogen chloride when exposed to light or heat. When exposed to sunlight for a long time or in a temperature environment above 100°C, PVC will decompose into hydrogen chloride gas and further auto-catalytically decompose it. Therefore this material is not suitable for food packaging.

The above are several common components of plastic bags. Most of the plastic bags used in daily life are PE polyethylene plastic bags and PVC polyvinyl chloride plastic bags. Colorless and light-colored PE plastic bags should be used as much as possible.